In Multiples of Three/ Mythical Creatures

Today I snuck off to the Dollar Store while the kids were napping and Doug was writing a test for his class tonight. I needed to get the kids some more paper. Laila draws about 10 pictures a day, and writes letters and numbers, so they quickly run out.
While I was there, I picked up some more puzzles for Laila and Rogan, and tried to find one for Grant, but no luck. Grant is now at that age where, if his older siblings get something, he has to have something too, or he pitches a fit. So, I looked around at their crappy toys that are all made in China, for the least harmful thing. The only thing I could come up with was a little pooh bear plastic figurine. So, I bought that as his diversion. Then I headed off to the library to pick them up some more books and educational movies.
When I got home, they were all awake and outside. They bombarded me when they saw the bags in my hands, asking if I brought them anything. So, I set them down and gave them the puzzles and paper. When the older two were excited and off with their things, I opened up Grant's toy and gave it to him. He was so excited, saying, "POOH! POOH!" Laila heard him and rushed over, saying "Where is my Pooh bear? I want a Pooh bear!"
I told her that she got paper and a nice puzzle, and Grant can't play with those things, so I got him a Pooh bear. She then proceeded to protest, and cry and say that she "Hates puzzles! Why do I always buy her dumb puzzles, and never the 'fun' toys?!"
She proceeded to whine and complain the rest of the day, even after she opened her puzzle and did it, she said, "See Mommy, I did this STOOOPID puzzle, now I want a Pooh bear so I can have fun!"
She annoyed me so much with this attitude, I wanted to lock her up in her room the rest of the day! Why do I have to buy everything the exact same in multiples of three?! Does every kid do this? When do they grow out of this, or will they ever grow out of it? How in the world do you teach a kid to be happy when someone else gets something?
I always dread present-related holidays and birthdays because of this factor. Birthdays are particularly bad as one kid gets sung to, cake, multiple gifts, phone calls, cards, balloons, etc, while the others don't receive a thing. I usually get all of them something at each birthday, but am considering not even celebrating birthdays for a while, as it seems to get completely out of hand. I try to be happy for the kid whose birthday it is, but at the same time dealing with tantrums from the other two! Maybe instead of gifts, we will just ask people to send money so we can do something fun as a family, because it does take all of us to keep each other happy and celebrate each other.
Doug and I have even been considering phasing out Santa and the Easter Bunny now. It annoys us to no end that we lie to our children about these mythical characters, then they complain that "Santa didn't bring exactly what they wanted, and they were good so they deserve it" (for example, since my kids never see any ads for toys, they make things up that don't really exist in the stores). Then, when they do get something they really like, they give all the credit to the mythical creature, and not us, proclaiming that "Santa is the best in the world!" or such. Doug and I want this kind of favor from our kids, don't we as parents deserve to have our kids think we are the best? We think so. But how do we tell them the truth about Santa without hurting them? It is really getting tricky with Laila who waits in anxious anticipation until the next mythical creature steps into her life...the Tooth Fairy!
I know...Santa and The Easter Bunny was so much fun when I was a kid, so this is hard on us. However, my kids have never really celebrated Halloween, the trick-or-treating part, and they don't even know what they are missing. I mean, certain religions, like Judaism don't do Santa, but some of those kids seem jealous to me. I am sure some of them aren't though. The other hard part about it is that relatives try and uphold it. The good thing though is that they are the youngest in our families, no other family member is a believer still. Needless to say, we are definitely torn on this issue.
Last year we just gave them one present from Santa, and the rest from us and the family. We gave them the biggest presents too, so Santa seemed like a cheap skate. As for the Easter Bunny, he only brought eggs, the other toys and goodies came from us. Maybe we will stick to that for a while until we figure it out.